TOC Click Implementation

Goal

Implement the TOC activation contract from the updated editor spec: navigation-only activation in edit/readonly, no block-selection or caret-entry side effects, keyboard activation on Enter/Space.

Phases

• Inspect current TOC navigation / selection code after revert.
• Add targeted tests for navigation-only activation and keyboard activation.
• Implement the TOC activation change.
• Verify with tests, build/typecheck, lint, and browser proof.

Notes

• Spec says TOC generated entries are overlay navigation controls, not block-selection targets.
• Prior attempt to preserve visible block selection was wrong; it fought the selection plugin design.